1. Technical Field
The present invention relates to the forwarding of e-mail messages, and especially to preventing forwarding of offensive, unnecessary, and junk e-mail messages while allowing forwarding of useful and important e-mails.
2. Related Art
In recent years, communication service providers have provided a variety of Internet related communication services. An e-mail communication service is a typical example of such a service. When a customer makes a contract with a communication service provider, the communication service provider assigns to the customer an e-mail management apparatus for providing the e-mail communication service; and provides the customer with an e-mail account, by use of which the customer may access the e-mail management apparatus. A “mailbox” is created in the e-mail management apparatus, corresponding to the e-mail account of the customer. The mailbox is a storage location for storing received e-mails addressed to the customer. Then, an e-mail address for representing a destination of an e-mail is assigned to the customer in the composite form of the e-mail account of the customer and an identifier for identifying the e-mail management apparatus (a domain name assigned to e-mail management apparatus, for example).
A common problem for e-mail users is so-called ‘junk mail’. Junk mail is sent for the purpose of advertising and is sent to many e-mail addresses. Most junk mail messages are offensive and/or useless for the customer receiving them. Therefore, it is desirable to provide a method and an apparatus to prevent such junk mail being forwarded to customers.
A number of ideas have been proposed to provide a method and/or an apparatus for preventing the forwarding of junk e-mail messages to customers. For example, Japanese patent publication JP 2001-A-257712 discloses a system which determines that a received e-mail message is junk mail and deletes it without forwarding it, when the received e-mail has features which are common to a predetermined number of received e-mails addressed to a plurality of e-mail addresses. However, in such a system it is difficult to use consistent criteria for determining whether a received message is junk mail, as a sender may send junk mail messages in a variety of formats.
Changing e-mail accounts is a well-known method of effectively avoiding receipt of junk mail. Since an e-mail address is bound to an e-mail account as described above, use of a different e-mail account has the same effect as use of a different e-mail address. Accordingly, when a new e-mail account is used, junk mail will not be received until the e-mail address bound to the new e-mail account becomes known to a sender. However, if a customer discards an e-mail account, valuable messages stored in the mailbox will be deleted and become inaccessible.